TITRIMETRIC MEASUREMENTS

Titrimetric measurement involves titrating alkaline HCN solution against a standard solution of silver nitrate using a silver sensitive indicator, p-... 

Titrimetric measurements alkalinity titration for carbonate and bicarbonate ion determinations, argentometric and potentiometric titrations for determining chloride, and iodo-metric titration for sulfite, chlorine, and dissolved oxygen. 

A highly interesting and often overlooked aspect of this structure proof was brought out by the titrimetric measurements on nucleosides and their free bases by Levene, Bass, and Simms.1M They reasoned, quite justifiably, that uracil should possess two acidic dissociation constants, because of the presence of two potentially dissociable protons in the molecule. (At that time, the problem as to the position of attachment of the carbohydrate to the nitrogenous base had essentially been diminished to a choice between positions 1 and 6.) They demonstrated in an early paper109(a) that uracil possesses two acidic dissociation constants (9.28 and 18.66). If the sugar radical were substituted on position 6 of uridine, both of the dissociation constants of uracil should be demonstrable in uridine whereas, if substitution by the sugar were on position 1, only one of these pKa values should be observable. 

They showed that, in fact, uridine possesses two acidic dissociations, and on this basis would have had to conclude that the sugar moiety was affixed to position 6 (At this time, the 5, 6 -bi8(phenylhydrazino)uridine107 had already been prepared, which excluded position 6. ) A re-examination109(b) of the titrimetric measurements revealed that (a) uracil possesses only one acidic dissociation (pKa 9.42), (b) the higher acidic pKa value for uridine (12.52) is due to dissociation of the sugar moiety rather than being that of the pyrimidine, and (c) 1- and 3-methyluracil possess only one dissociation constant each. Therefore, they concluded that the dissociation constants of uridine and uracil did not contradict the theory of the union at position... 

Application and Principle This procedure is used to determine glucose oxidase activity in preparations derived from Aspergillus niger var. The assay is based on the titrimetric measurement of gluconic acid produced in the presence of excess substrate and excess air. 

This evidence, based upon titrimetric measurements, is supported by measurements of the rates of hydrolysis and of fluorine exchange in mixtures of HBF4 and HF. Both hydrolysis and exchange are almost first order in both BF4 and H" ". The rate of fluorine exchange is close to four times the rate of hydrolysis. Thus only the first hydrolytic step is slow. The rate coefficients for exchange fit the equation... 

The incubation of a tissue homogenate or tissue slice with a choline ester reveals the presence of cholinesterase activity in the tissue [34]. This may be measured as a fall in the pH of the medium due to the production of acetic acid from acetylcholine [35], the manometric measurement of carbon dioxide released from bicarbonate by the liberated acetic acid, the titrimetric measurement of the amount of alkali necessary to maintain the incubation medium at... 

Wet chemistry Procedures that involve distillations, colorimetric determinations, and titrimetric measurements. Examples of analytes that are routinely quantitatively determined by wet chemical methods include cyanides, methylene blue active surfactants, biological and chemical oxygen demands, abbreviated BOD, and COD. 

Subsequent related work by Hayashi, Ogoshi and coworkers then served to show that rapid ET can also be achieved by use of aaaa-/weso-tetrakis(2-hydroxy-l-naphthyljporphyrin zinc complex (122) and aaoLOL-meso-tetrakis(7-hydroxy-l-naphthyl)porphyrin zinc complex (123).The.se affinities for TMBQ were determined, by titrimetric measurement of visible spectra, to be... 

FTIR photoacoustic spectroscopy was used to determine the extent of acylation in acetylated jute samples quantitatively and results were compared with those obtained by standard wet chemical titrimetric measurements. 12 refs. 

Titrimetric measurements were used to estimate the average number of carboxylic groups grafted onto each compatibilizer molecular chain. This informa-... 

Chan and Tobe used fast-flowing pipets to titrimetrically measure the rates of base hydrolysis of cobalt(III) complexes whose half-lives are as small as 45 sec. Complex concentrations used in the present study are in the range of 9.0 X lO toS-O X 10 M. The ratio of[OH ] [complex] was varied from 1 1 to 20 1 at 0.0 but was held at 1 1 for all other temperatures. Under these conditions, the half-lives were far in excess of the lower limits imposed by Chan and Tobe. the data obtained at 0 is considered to... 

The quantity of amylose may be determined in starches or other mixtures by a characteristic reaction with iodine. Amylose combines with iodine to form a deep-blue complex, which is responsible for the color of starch indicators. Amylopectin solutions are colored blue-violet or purple. The intensity of the amylose-iodine complex can be measured in a spectrophotometer, or titrimetric measurements can be made of the amount of iodine taken up in forming the amylose-iodine complex. 

A.K. Gemaey, B. Petersen, J.-P. Ottoy, and P. Vanrolleghem. Activated sludge monitoring with combined respirometric-titrimetric measurements. Water Res., 35 1280-1294, 2001. 

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